Many mental health problems involve a failure to apprehend accurately the nature of the social world, particularly including the psychological properties of oneself and others. Moreover, the accurate judgment of personality is an important aspect of clinical diagnosis and practice, and has many other practical implications. The present research is designed to address the circumstances that make the accurate judgment of personality more and less likely, including such possible influences as the nature of the trait being judged, the type of behavior being predicted, and individual differences among the judges and the persons they judge. The study will gather a large variety of information about the personality and behavior of 160 college age subjects (80 males and 80 females). This information will include videotaped samples of spontaneous behavior with two different opposite sex peers in two different situations, the subjects' descriptions of their own personalities through the Q-sort, self act reports, descriptions provided by knowledgeable informants, and a number of personality and social skill inventories. Information gathered about the informants themselves will also include various inventories and tests. These data will allow examination of a wide variety of possible influences on the accuracy of judgments of personality as defined both via inter-rater agreement and by the ability of the judgments to predict behavior. The ultimate goals of the research are a better understanding of the factors that make our judgments more and less likely to be accurate, and a contribution to techniques for improving accuracy.